[tip:x86/apic] x86/smpboot: Sanitize uniprocessor init

From: tip-bot for Thomas Gleixner
Date: Thu Jan 22 2015 - 09:32:13 EST


Commit-ID: 613c25efbdc763ee8b9d732368106d2456279356
Gitweb: http://git.kernel.org/tip/613c25efbdc763ee8b9d732368106d2456279356
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 15 Jan 2015 21:22:42 +0000
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 22 Jan 2015 15:10:56 +0100

x86/smpboot: Sanitize uniprocessor init

The UP related setups for local apic are mangled into smp_sanity_check().

That results in duplicate calls to disable_smp() and makes the code
hard to follow. Let smp_sanity_check() return dedicated values for the
various exit reasons and handle them at the call site.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20150115211703.987833932@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/smpboot.c | 37 ++++++++++++++++++++++++++-----------
1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index d538709..fe8783d 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -990,6 +990,8 @@ void arch_disable_smp_support(void)
*/
static __init void disable_smp(void)
{
+ pr_info("SMP disabled\n");
+
disable_ioapic_support();

init_cpu_present(cpumask_of(0));
@@ -1003,6 +1005,13 @@ static __init void disable_smp(void)
cpumask_set_cpu(0, cpu_core_mask(0));
}

+enum {
+ SMP_OK,
+ SMP_NO_CONFIG,
+ SMP_NO_APIC,
+ SMP_FORCE_UP,
+};
+
/*
* Various sanity checks.
*/
@@ -1050,10 +1059,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
if (!smp_found_config && !acpi_lapic) {
preempt_enable();
pr_notice("SMP motherboard not detected\n");
- disable_smp();
- if (APIC_init_uniprocessor())
- pr_notice("Local APIC not detected. Using dummy APIC emulation.\n");
- return -1;
+ return SMP_NO_CONFIG;
}

/*
@@ -1077,7 +1083,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
boot_cpu_physical_apicid);
pr_err("... forcing use of dummy APIC emulation (tell your hw vendor)\n");
}
- return -1;
+ return SMP_NO_APIC;
}

verify_local_APIC();
@@ -1087,12 +1093,10 @@ static int __init smp_sanity_check(unsigned max_cpus)
*/
if (!max_cpus) {
pr_info("SMP mode deactivated\n");
- disable_ioapic_support();
- apic_bsp_setup();
- return -1;
+ return SMP_FORCE_UP;
}

- return 0;
+ return SMP_OK;
}

static void __init smp_cpu_index_default(void)
@@ -1132,10 +1136,21 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
}
set_cpu_sibling_map(0);

- if (smp_sanity_check(max_cpus) < 0) {
- pr_info("SMP disabled\n");
+ switch (smp_sanity_check(max_cpus)) {
+ case SMP_NO_CONFIG:
disable_smp();
+ if (APIC_init_uniprocessor())
+ pr_notice("Local APIC not detected. Using dummy APIC emulation.\n");
+ return;
+ case SMP_NO_APIC:
+ disable_smp();
+ return;
+ case SMP_FORCE_UP:
+ disable_smp();
+ apic_bsp_setup();
return;
+ case SMP_OK:
+ break;
}

default_setup_apic_routing();
--
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